Don't suppress notices during startup flow

NoticeResponses received during the startup flow were previously being
dropped on the floor. Instead stash them away so they can be delivered
to the user after the startup flow is complete.

tokio-postgres/src/connect_raw.rs

@@ -13,7 +13,7 @@ use postgres_protocol::authentication::sasl;
 use postgres_protocol::authentication::sasl::ScramSha256;
 use postgres_protocol::message::backend::{AuthenticationSaslBody, Message};
 use postgres_protocol::message::frontend;
-use std::collections::HashMap;
+use std::collections::{HashMap, VecDeque};
 use std::io;
 use std::pin::Pin;
 use std::task::{Context, Poll};
@@ -23,6 +23,7 @@ use tokio_util::codec::Framed;
 pub struct StartupStream<S, T> {
     inner: Framed<MaybeTlsStream<S, T>, PostgresCodec>,
     buf: BackendMessages,
+    delayed: VecDeque<BackendMessage>,
 }
 
 impl<S, T> Sink<FrontendMessage> for StartupStream<S, T>
@@ -91,6 +92,7 @@ where
     let mut stream = StartupStream {
         inner: Framed::new(stream, PostgresCodec),
         buf: BackendMessages::empty(),
+        delayed: VecDeque::new(),
     };
 
     startup(&mut stream, config).await?;
@@ -99,7 +101,7 @@ where
 
     let (sender, receiver) = mpsc::unbounded();
     let client = Client::new(sender, config.ssl_mode, process_id, secret_key);
-    let connection = Connection::new(stream.inner, parameters, receiver);
+    let connection = Connection::new(stream.inner, stream.delayed, parameters, receiver);
 
     Ok((client, connection))
 }
@@ -332,7 +334,9 @@ where
                     body.value().map_err(Error::parse)?.to_string(),
                 );
             }
-            Some(Message::NoticeResponse(_)) => {}
+            Some(msg @ Message::NoticeResponse(_)) => {
+                stream.delayed.push_back(BackendMessage::Async(msg))
+            }
             Some(Message::ReadyForQuery(_)) => return Ok((process_id, secret_key, parameters)),
             Some(Message::ErrorResponse(body)) => return Err(Error::db(body)),
             Some(_) => return Err(Error::unexpected_message()),

tokio-postgres/src/connection.rs

@@ -52,7 +52,7 @@ pub struct Connection<S, T> {
     parameters: HashMap<String, String>,
     receiver: mpsc::UnboundedReceiver<Request>,
     pending_request: Option<RequestMessages>,
-    pending_response: Option<BackendMessage>,
+    pending_responses: VecDeque<BackendMessage>,
     responses: VecDeque<Response>,
     state: State,
 }
@@ -64,6 +64,7 @@ where
 {
     pub(crate) fn new(
         stream: Framed<MaybeTlsStream<S, T>, PostgresCodec>,
+        pending_responses: VecDeque<BackendMessage>,
         parameters: HashMap<String, String>,
         receiver: mpsc::UnboundedReceiver<Request>,
     ) -> Connection<S, T> {
@@ -72,7 +73,7 @@ where
             parameters,
             receiver,
             pending_request: None,
-            pending_response: None,
+            pending_responses,
             responses: VecDeque::new(),
             state: State::Active,
         }
@@ -82,7 +83,7 @@ where
         &mut self,
         cx: &mut Context<'_>,
     ) -> Poll<Option<Result<BackendMessage, Error>>> {
-        if let Some(message) = self.pending_response.take() {
+        if let Some(message) = self.pending_responses.pop_front() {
             trace!("retrying pending response");
             return Poll::Ready(Some(Ok(message)));
         }
@@ -158,7 +159,7 @@ where
                 }
                 Poll::Pending => {
                     self.responses.push_front(response);
-                    self.pending_response = Some(BackendMessage::Normal {
+                    self.pending_responses.push_back(BackendMessage::Normal {
                         messages,
                         request_complete,
                     });

tokio-postgres/tests/test/main.rs

@@ -570,6 +570,45 @@ async fn copy_out() {
     assert_eq!(&data[..], b"1\tjim\n2\tjoe\n");
 }
 
+#[tokio::test]
+async fn notices() {
+    let long_name = "x".repeat(65);
+    let (client, mut connection) =
+        connect_raw(&format!("user=postgres application_name={}", long_name,))
+            .await
+            .unwrap();
+
+    let (tx, rx) = mpsc::unbounded();
+    let stream = stream::poll_fn(move |cx| connection.poll_message(cx)).map_err(|e| panic!(e));
+    let connection = stream.forward(tx).map(|r| r.unwrap());
+    tokio::spawn(connection);
+
+    client
+        .batch_execute("DROP DATABASE IF EXISTS noexistdb")
+        .await
+        .unwrap();
+
+    drop(client);
+
+    let notices = rx
+        .filter_map(|m| match m {
+            AsyncMessage::Notice(n) => future::ready(Some(n)),
+            _ => future::ready(None),
+        })
+        .collect::<Vec<_>>()
+        .await;
+    assert_eq!(notices.len(), 2);
+    assert_eq!(
+        notices[0].message(),
+        "identifier \"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx\" \
+         will be truncated to \"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx\""
+    );
+    assert_eq!(
+        notices[1].message(),
+        "database \"noexistdb\" does not exist, skipping"
+    );
+}
+
 #[tokio::test]
 async fn notifications() {
     let (client, mut connection) = connect_raw("user=postgres").await.unwrap();